While there are many different reasons for migration and many distinct theoretical and ideological attitudes to it, two features are common to nearly all discourses on the subject: a hostile attitude to migration and a clash between the logic applied to migration and that applied to other questions of human rights.
The Universal Declaration of Human Rights concedes the right to be a citizen of a country, to be free to move within that country, not to have a passport of that country withheld, to leave and re-enter that country at will and without restriction. And then - silence.
Accordingly, we have a universal human right to depart but not to arrive. Arrival is regarded as a privilege which each nation state can withhold or grant on the grounds of political expediency or other criteria unrelated to human rights. The only exception concerns asylum for bona fide political refugees. Recognition of their rights stemmed from the post-war realisation that the lack of a right of refuge for Jews and others contributed to Nazi genocide in the Thirties and Forties - but even these rights are now being severely curtailed.
Efforts to justify the exclusion of immigration from the list of human rights are unpersuasive. Philosophers tend to draw an analogy between a nation and a household. Since it is generally recognised that existing members of a household should have the right to leave, but that other people do not have the right to enter without the existing occupants' consent, the same should apply to nations.
However, this argument is entirely illogical. If the home is a suitable analogy for a country, it must also be a suitable analogy for a village, a city or a province. Yet no one argues that the citizens of Kingston in Surrey should have the right to control the entry of the citizens of neighbouring Surbiton.
The fact that a right is enshrined in the Universal Declaration, of course, is no guarantee that it will be observed in practice. It is a universal human right to have a job and enough to eat, but this has not eliminated unemployment nor hunger. But the declaration of these concepts as rights helps define, however loosely, some shared concept of what is desirable and acceptable.
Because the right of immigration is missing from the list of recognised human rights, a government minister is able to say that he or she advocates 'zero immigration' - as did French Interior Minister Charles Pasqua - without attracting censure. It would be unacceptable for a minister to advocate increased unemployment or hunger.
Certain political rights - to vote, to freedom of speech, not to suffer arbitrary detention etc have now become synonymous with human rights in general. The absence of these rights in a country is what justifies the right to political asylum elsewhere. A country's violation of the other universal human rights - to employment or adequate nutrition - do not guarantee its citizens the right to asylum elsewhere. In fact, Western Europe in recent years has taken exactly the opposite view. A distinction is increasingly being made between 'good' migrants who are fleeing political persecution and 'bad' migrants who are simply looking for a materially better life.
The distinction has been used to justify changes in European laws and constitutions and as the basis for the forced repatriation of Vietnamese boat people by the Hong Kong/British government. The United States, which roundly condemns Hong Kong, is doing precisely the same to Haitian migrants.
The discrepancy in the treatment of those fleeing a lack of political and those fleeing a lack of economic rights highlights another contradiction. The neo-liberal counter-revolution, which has so influenced economic ideas and policy since the end of the Seventies, has stressed on the one hand free trade and the free movement of capital, and on the other the importance of personal responsibility, self-reliance and self-help. 'Economic migration' would seem to be a perfect example of market virtue. But it appears that even in these days of globalisation, when goods and money can move freely, the labour market must stop at the frontier.
Even the most doctrinaire free- market economists hesitate to advocate free movement of people. On your bike, as Margaret Thatcher's minister Norman Tebbit said, and you are a saint shining with neo-liberal virtues. On your ferry, and you are a demon against whom great European democracies change their constitutions in panic.
The present rules relating to migration also tend to reduce the sum of human rights everywhere, since immigrants, even if they acquire legal rights to residence in their new country, often have fewer rights than the resident populations. Their presence may be conditional on good behaviour and they may not receive social benefits.
Further, immigrants often do not enjoy the right to vote in their new country. Because of this, the more people move, the less will be the proportion of the ruled population to whom a national government is electorally answerable.
The only thing that would prevent migration leading to a steady erosion of rights and democratic controls is for immigrants rapidly to acquire political and other rights, preferably through easy access to citizenship. Yet naturalisation is difficult everywhere, the rules governing it in most places are tightening, and many countries make ethnic origin a condition of naturalisation, something which excludes most immigrants from full rights for ever.
Many, however, never get anywhere near naturalisation. They fall into the black hole of human rights which has developed at the borders of the main receiving countries. Would-be migrants who are stopped at border controls risk interrogation and search, a spell in a transit camp with no contact with the rest of the world and forcible repatriation. They have no right to a lawyer nor opportunity to contact anyone who could help them. Temporary camps and residences can be as inaccessible as military establishments and agitation on detainees' behalf is often impossible because their fate is a well kept secret. Nearly all political economists see immigration primarily in the context of the labour market. They tend to regard emigration as a 'brain drain' and a disaster, and immigration as a threat to the national labour market because it is seen as potentially weakening the bargaining power of that country's labour force. They regard the remittances of migrants - which now amount to more than all development aid and are second only to oil as an export earner for the Third World - as bad for the economy of their country of origin: they blame these remittances for raising imports, consumption and inflation.
Much popular opposition to immigration is based on irrational prejudice, racism and the erroneous association of immigration with ills such as unemployment, increased crime and homelessness.
Comparison of the countries of the European Union shows, however, that those with fewer immigrants tend to have more unemployment. The fear that immigration will lower the bargaining power of labour in receiving countries also has much more basis in relation to illegal than legal immigration. The problem derives from illegality rather than from migration.
Some of the problems attributed to immigration also result from the general neglect of real social and economic problems by governments. The feeling against immigration is likely to grow in periods when governments fail to tackle the fundamental causes of social problems. Immigration does not create the conflict; it merely changes the way it manifests itself - and immigrants become popular scapegoats for government failure.
It will not be easy to stop the negative trajectory in attitudes to migration. But you do not have to believe in the unfettered power of ideology or logic to believe that part of the problem is the almost universal failure to regard the freedom to move as a basic human right. If there existed in the world a country inhabited by various ethnic groups, in which the richest and most powerful group divided the country into ethnic areas and forbade the poorer, less powerful groups to enter the privileged groups' areas except under strict conditions, there is a good chance that it would be declared a pariah by other nations for its denial of human rights.
Such a country did exist until very recently: South Africa under apartheid. And it was universally condemned. Yet, viewed as a whole, the world today is worse in these respects than South Africa under apartheid. On the right to move, and the rights of migrants when they have moved, the world is a macrocosm of the country which all other countries found impossible to accept.
The author teaches international economics and development in the University of the Basque Country in Bilbao. This is an abridged version of his article in the July-August issue of 'Index on Censorship', published this week, pounds 6.99.